Conventional incandescent lamps have an efficacy of 10 to 12 lumens per watt, so that a 60 W incandescent lamp (a common wattage) has a flux output of 600 to 720 lumens. In addition, the color temperature of these lamps is under 3000° K and they achieve a color rendering index (CRI) near 100. It would be desirable to have a retro-fit high efficiency solid state lamp that can replace a 60 to 75 W incandescent lamp, and that has a similar color temperature and a high CRI (above 85 and preferably 90 or more). Also, it would be desirable if the solid state lamp was dimmable (a major problem with the vast majority of the compact fluorescent bulbs that are at present the commonest substitutes for incandescent bulbs.) Finally, it would be desirable if the output from this solid state lamp replicate the spherical output from incandescent sources. Such a solid state device is especially needed at this time, because the European Union (EU) and the USA have mandated that incandescent lamp will be phased out in the near future (2010 for the EU). Current solid state replacement lamps are typically limited to a flux of around 400 to 480 lumens (equivalent to the flux output of a 40 W incandescent bulb), primarily because of thermal management issues. Also, the light output from these lamps does not match the spherical output from filament-based sources.